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| author | Peter Marheine <pmarheine@chromium.org> | 2022-12-15 11:33:19 +1100 |
|---|---|---|
| committer | Chromeos LUCI <chromeos-scoped@luci-project-accounts.iam.gserviceaccount.com> | 2023-01-12 22:52:09 +0000 |
| commit | 49abac39678928a242f94115f523ba462146412a (patch) | |
| tree | 4f49575ca917686881027e18bfa17d6cbef6ece5 /docs | |
| parent | 9a9669c83100f8833d066e8a0e58a561075c3e9f (diff) | |
| download | chrome-ec-49abac39678928a242f94115f523ba462146412a.tar.gz | |
Default charger current derating to 5%
Not derating seems like a common pitfall that can cause problems with
some chargers, so set a reasonably conservative default.
5% is chosen as the most common derating factor used among boards today
(counting occurrences in source code, so this may undercount 5%
occurrences because several projects set 5% at the project rather than
board-level):
1. 38 x 5%
2. 23 x 4%
3. 6 x 10%
3. 2 x 3%
4. 1 x 2%
Boards that currently configure this setting are modified only to
continue building without warnings regardless of whether they use the
new default value in order to signal that they were explicitly
configured.
BUG=b:260774380
TEST=make buildall / zmake build -a
BRANCH=none
Change-Id: I017849d38572fbc48090ae1fa2c539b808e426f9
Signed-off-by: Peter Marheine <pmarheine@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4109651
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Code-Coverage: Zoss <zoss-cl-coverage@prod.google.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/low_battery_startup.md | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/docs/low_battery_startup.md b/docs/low_battery_startup.md index 1f94d4956e..c82268a308 100644 --- a/docs/low_battery_startup.md +++ b/docs/low_battery_startup.md @@ -427,3 +427,13 @@ Optional. Similar to `CONFIG_CHARGER_MIN_POWER_MW_FOR_POWER_ON`, this is the minimum charger power needed to boot even when the battery is less than `CONFIG_CHARGER_MIN_BAT_PCT_FOR_POWER_ON_WITH_AC` + +### `CONFIG_CHARGER_INPUT_CURRENT_DERATE_PCT` + +Optional, default 5%. + +This option reduces the charger's programmed current limit below the detected +current limit for a given charger in an attempt to ensure that load transients +won't overcurrent the source. Devices that require a lot of power to boot may +need to either decrease the derating factor (if behavior remains acceptable when +decreased) or increase `MIN_POWER_MW` settings to compensate.
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